Metal plating-based electrical energy storage cell

ABSTRACT

The present disclosure provides an electrochemical storage cell including a battery. The battery includes an alkali metal anode having an anode Fermi energy, an electronically insulating, amorphous, dried solid electrolyte able to conduct alkali metal, having the general formula A 3-x H x OX, in which 0≤x≤1, A is the alkali metal, and X is at least one halide, and a cathode including a cathode current collector having a cathode Fermi energy lower than the anode Fermi energy. During operation of the electrochemical storage cell, the alkali metal plates dendrite-free from the solid electrolyte onto the alkali metal anode. Also during operation of the electrochemical storage cell, the alkali metal further plates on the cathode current collector.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/360,853 filed Jul. 11, 2016, and which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to electrochemical storage cells, and inparticular, to a metal plating-based electrochemical energy storagecell, which may include a battery, such as a rechargeable-battery, or acombined battery/supercapacitor.

BACKGROUND

Batteries

A battery, as used herein, refers to a cell having two electrodes, ananode and a cathode, separated by an electrolyte. The cell may be anelectrochemical cell. Materials in the electrodes may be bothelectronically and chemically active. The anode may be a chemicalreductant and the cathode may be a chemical oxidant. Thus, both theanode and the cathode may be able to gain and lose ions, typically thesame ion, which is referred to as a ‘working ion’ of the battery. Theelectrolyte may be chemically active while being electronically passive.The chemical activity of the electrolyte is exhibited by the ability togain and lose ions, which are typically the working ion. The electrolyteis generally an electronic insulator, and may not promote the movementof electrons within the battery.

The battery may operate via a chemical reaction between the twoelectrodes that has an electronic and an ionic component, and is hencecalled an ‘electrochemical reaction’. The electrolyte conducts theworking ion inside the cell and, as an electronic insulator, enableselectrons involved in the reaction to pass through an external circuit.

When a liquid or polymer electrolyte is used in a battery, a separatorthat remains an electronic insulator on contact with the two electrodesmay be used to keep the two electrodes from electronically contactingeach other inside the cell. The separator may be permeated by the liquidor polymer electrolyte to allow ionic conduction between the twoelectrodes. In some battery implementations, a solid electrolyte may beused as the separator. Solid electrolytes may be used alone or with aliquid or polymer electrolyte contacting one or both electrodes. Solidelectrolytes may also function as a separator, such that a separateseparator is not needed.

Batteries are often named after the working ion. For instance, lithiumion (Li+) is the working ion in a lithium-ion (Li-ion) battery. Sodiumion (Na+) is the working ion in a sodium-ion (Na-ion) battery. Li-ionbatteries are commonly used in electronic devices, power tools, andelectric vehicles. A Li-ion battery is assembled in a discharged stateto enable preparation of a high-voltage cathode and an anode free ofmetallic lithium, while a flammable organic-liquid electrolyte may beused. Incremental improvements in Li-ion batteries have been obtained bythe fabrication of complex electrode morphologies, but the carbon anodehas limited capacity and may be plated by metallic lithium under anexcessively high rate of charge. In addition, oxygen may be lost from alayered-oxide cathode if the cell is overcharged. Managing a large stackof cells over many charge and discharge cycles may increase the cost ofa large, multi-cell battery, such as those used in electric vehicles.Moreover, the ability to increase the volumetric capacity of batteries,which is applicable for portable batteries, among other applications,has been limited. Finally, organic-liquid electrolytes suitable for mostLi-ion batteries are flammable, posing safety risks, particularly if thebatteries form dendrites or are damaged in some way that allowselectronic contact between the cathode and the anode within the battery.

Supercapacitors

Supercapacitors utilize the capacitances of an electronic double layerat an electrode-electrolyte interface where positive and negativecharges are separated by only atomic dimensions. Moreover, if theelectrolyte has a large dielectric constant as a result of the presenceof electric dipoles, the capacitance can be increased even further. Thesupercapacitor stores electric power as static electric charge ratherthan as chemical energy even where the supercapacitor may contain afaradaic component of electrical-energy storage.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, which relate toembodiments of the present disclosure.

FIG. 1 is a schematic diagram of a catalytic redox-center-relay battery.

FIG. 2 is a schematic of the energy profile of a stable battery with anelectrolyte energy window having an energy gap Eg=LUMO−HOMO, or lowestunoccupied molecular orbital (LUMO)—highest occupied molecular orbital(HOMO).

FIG. 3 is a plot of discharge voltage versus the capacity of a Li/S cellin the form of a Li/Li-glass/Cu cell containing a sulfur (S) relay.

FIG. 4 is a plot of discharge voltage versus the capacity of the Li/Scell of FIG. 3 relative to the capacity of the lithium anode.

FIG. 5 is a plot of storage efficiency and coulombic efficiency ofelectric-power storage in the Li/S cell of FIG. 3 with adischarge/charge cycle of 10 h charge, 2 h rest, 10 h discharge, 2 hrest for a large number of cycles.

FIG. 6 is a plot of storage efficiency and coulombic efficiency ofelectric-power storage in a Na/Na-glass/Cu cell with a ferrocenemolecule as the redox center for plating sodium on a copper currentcollector.

FIG. 7 is a plot of charge/discharge voltage profiles versus time of aLi/S cell, in which the cell is self-charged.

FIG. 8 is a charge/discharge voltage plot of an Al/Li-glass/Cu cellshowing, inset, an increase to over 100% in the coulomb efficiency ofelectric-power storage on successive self-charges at open-circuit owingto plating of metallic lithium on the aluminum anode.

DETAILED DESCRIPTION

The disclosure relates to metal plating-based electrical energy storagecells. The cells may include batteries, particularly rechargeablebatteries, and various combinations of batteries and supercapacitors.More specifically, the present disclosure describes all-solid-staterechargeable cells in which the cation of a metal plated on the anodecurrent collector during charge is supplied by the electrolyte.Batteries according to the present disclosure may have a high energystorage capacity with high charge rates, and long operational lifetimesover many cycles. Supercapacitors according to the present disclosuremay have an optimized or increased volumetric stored energy density.

Batteries and supercapacitors according to the present disclosure maycontain a solid electrolyte that contains electric dipoles that areoriented parallel to one another and if the electrodes or currentcollectors have a large energy difference in electrochemical potential,a battery cell that incorporates a series connection of the faradaic andcapacitive electrical energy storage may exhibit an enhanced energydensity. Unlike the traditional Li-ion battery, which has a carbonelectrode and a layered oxide cathode and is limited in the rate andextent of charge and discharge, the present disclosure provides a safe,all-solid-state battery or supercapacitor cell that may provide a largevolumetric energy density, a fast rate of charge and discharge, and along cycle life.

The present disclosure describes all-solid-state rechargeable cells inwhich the cation of a metal plated on the anode current collector duringcharge is supplied by the electrolyte.

In a secondary (rechargeable) cell, an alkali metal on the cathodecurrent collector is plated back on the anode without the formation ofanode dendrites. The anode dendrites may be prevented if the alkalimetal wets the solid-electrolyte surface, and the anode is free of apassivating solid-electrolyte interphase (SEI) layer, such that thesolid electrolyte has a lowest unoccupied molecular orbital (LUMO) at anenergy above μA, which is the Fermi energy of the anode. As disclosedherein, such a solid electrolyte may enable the cell to be safe and theefficiency of electrical energy storage in the cell can approach 100%with a long cycle life.

The storage of electrical energy as chemical energy in the battery cellsdisclosed herein may be supplemented by the storage of electrical energyas electrostatic energy, as in a supercapacitor. The electrostaticenergy may be provided by the formation of an electric double layer atthe electrode-electrolyte interface. Moreover, an amount ofelectrostatic energy stored may further be increased if the electrolytecontains electric dipoles, particularly where the electric dipoles areoriented parallel to one another. The rates of charge and discharge ofthe electrostatic energy stored in the cells disclosed herein may berelatively high with high efficiency.

In an electrochemical cell, such as a battery cell, of the presentdisclosure, a metal may be plated from the solid electrolyte. The metalplated may be the metal form of the working ion. For example, the metalmay be an alkali metal, such as lithium (Li), sodium (Na), or potassium(K), or magnesium (Mg) or aluminum (Al). The metal is platedbeneficially on a cathode current collector, such as a copper (Cu),silver (Ag), zinc (Zn), or gold (Au) metal, or an alloy thereof cathodecurrent collector. The plating may occur without the formation ofdendrites or other metal structures harmful to energy storage cellperformance.

FIG. 1 is a schematic diagram of a catalytic redox-center-relay battery10, which includes a cathode 20, an anode 30 and an electrolyte 40.Battery 10 may be connected to an external circuit 50, which may includea load that uses stored energy upon discharge, or a power supply thatprovides energy to be stored upon charge, if battery 10 is rechargeable.

Anode 30 may include a current collector, which may include the workingion. The current collector may simply be the metal of the working ion.In some instances, the current collector may be an alloy of the metal ofthe working ion and another metal. Anode 30 may be substantially thesame as the current collector. In some embodiments, anode 30 may includeother or different materials than the current collector.

Electrolyte 40 may be a solid electrolyte, which may be used alone or incombination with a liquid or polymer electrolyte. Thus, electrolyte 40may have the same or different composition at cathode 20 versus at anode30. The solid electrolyte may have an ionic conductivity comparable tothat of an organic-liquid electrolyte and a large dielectric constantassociated with electric dipoles in the solid electrolyte that can beoriented parallel to one another.

In particular, the solid electrolyte may be a glass or an amorphoussolid that may be water-solvated and may conduct monovalent cations suchas Li+, Na+, or H+, or mixtures thereof. The solid electrolyte may be anelectronic insulator. When the solid electrolyte conducts Li+, Na+, ormixtures thereof, the solid electrolyte may be dried. When the solidelectrolyte conducts H+, the solid electrolyte may not be dried. Such anelectrolyte is described in detail in PCT/US2016/036661, which isincorporated by reference herein in its entirety.

The dried, water-solvated glass/amorphous solid that conducts Li+, Na+,or mixtures thereof, may be formed by transforming a crystallinesodium-ion (Na+) or a crystalline lithium-ion (Li+) electronic insulator(or its constituent precursors comprising at least one Na+ or Li+ bondedto oxygen (O), hydroxide (OH), or to at least one halide into awater-solvated glass/amorphous Na+ or Li+ ion-conducting solid) byadding water in an amount less than or equal to the water solvationlimit of the glass/amorphous solid. A glass-forming oxide, sulfide, orhydroxide may also be added and the resulting material may be heated toexpel volatile constituents. The crystalline, electronic insulator orits constituent precursors may include a material with the generalformula A3-xHxOX, wherein 0≤x≤1, A is the at least one alkali metal, andX is the at least one halide. It may also include a glass-formingadditive including at least one, or at least two, of an oxide, ahydroxide, and a sulfide. The glass-forming additive may include atleast one, or at least two, of Ba(OH)2, Sr(OH)2, Ca(OH)2, Mg(OH)2,Al(OH)3, or BaO, SrO, CaO, MgO, Al , B2O3, Al2O3, SiO2, S and Li2S. Thedried, water-solvated glass/amorphous solid may include less than 2 molepercent of the glass-forming additive. The glass-forming additive mayadjust the glass transition temperature Tg of the water-solvatedglass/amorphous solid. The halide may comprise chlorine (Cl), bromine(Br), or iodine (I), or combinations thereof. At least a portion of thehalide may exit the water-solvated glass/amorphous solid as a hydrogenhalide gas. The hydroxide may react to form H2O that exits thewater-solvated glass/amorphous solid as gaseous H2O.

The H+-conductive water-solvated electrolyte may be formed bytransforming a crystalline material including at least one alkali oralkaline-earth cation bonded to at least one acidic polyanion into aglass/amorphous solid by adding water in an amount less than or equal tothe solvation limit in the crystalline material such that waterdissociates into hydroxide (OH—) anions that coordinate to the cationsto form polyanions, while the water may also dissociate into protons(H+) that are mobile in a framework of an acidic oxide and thepolyanions. The acidic polyanion may include (SO4)2- or (PO4)3- or both.

The H+-conductive water-solvated glass/amorphous solid may also beformed by transforming a crystalline electronic insulator including atleast one acidic polyanion and at least one cation into a water-solvatedglass/amorphous proton (H+)-conducting solid by adding water in anamount less than or equal to the water solvation limit of thecrystalline electronic insulator. The cation(s) may be stabilized in theform of a stable hydroxide polyanion(s). The acidic polyanion mayinclude a phosphate (PO4)3- polyanion or a sulfate (SO4)2- polyanion or(SiO4)4- polyanion or combinations thereof. The cation may include abarium (Ba2+) ion, a potassium (K+) ion, a rubidium (Rb+) ion, or acesium (Cs+) ion or combinations thereof. The stable hydroxide polyanionmay include (Ba(OH)x)2-x ,(K(OH)x)1-x, (Rb(OH)x)1-x or (Cs(OH)x)1-x orcombinations thereof.

Cathode 20 includes cathode current collector 70. Cathode 20 may alsoinclude catalytic redox-center-relay 60 in electronic contact withcathode current collector 70. Catalytic redox-center-relay 60 may be acoating or a layer covering cathode current collector 70. Catalyticredox-center-relay 60 may cause the working ion to plate onto cathodecurrent collector 70. Catalytic redox-center-relay 60 may include anelement, such a sulfur (S), a molecule, such as ferrocene (Fe(C□H□)□),or a variable compound, such as lithium iron phosphate (LixFePO4, where0≤x≤1).

Cathode 20 may further include a surface conductive film (not shown),such as carbon, on the current collector.

Suitable materials for use in cathode 20, anode 30, and electrolyte 40may be selected based upon electrical and chemical energycharacteristics of the battery and of the materials. Overall, thecharacteristics of the materials in combination are such that theworking ion is enabled to plate onto cathode current collector 70, or aconductive film covering the surface of cathode current collector 70, ifpresent. Catalytic-center-relay 60, which may be a certain molecule(s),a film, or an added particle, may further facilitate metal plating, whenpresent.

On discharge, a battery delivers a current Idis at a voltage Vdis toprovide electric power Pdis (Pdis=IdisVdis) for the time Δtdis it takesto complete the chemical reaction between the two electrodes. The celldensity of chemical energy that is delivered as electric power Pdis at aconstant current Idis=dq/dt (q=state of charge) is given by:ΔE _(dis)=∫₀ ^(Δt) P _(dis) dt=∫ ₀ ^(Q(I)dis) V(q)_(dis) dq=<V(q)_(dis)>Q(I _(dis))  (1)Q(I _(dis))=∫₀ ^(Q(I) ^(dis) ⁾ dq per unit weight or volume  (2)V(q)_(dis) =V _(oc)−η_(dis)(I)  (3)where Q(I_(dis)) is the cell capacity. The open-circuit voltage V_(oc)is given by:V _(oc)=(μ_(A)−μ_(C))/e   (4)is the difference between the electrochemical potentials μ_(A) and μ_(C)at the anode and cathode divided by the magnitude e of the electroncharge e. The ohmic loss η_(dis)(I) inside the cell is given by:η_(dis)(I)=I _(dis)R_(b,dis)  (5)where R_(b,dis) is the total internal resistance to the transfer of theionic component of the cell chemical reaction inside the cell ondischarge. The cation transferred by the electrolytes is the working ionof the cell, and R_(b)=R_(ct)+R_(i) contains the resistance to chargetransfer of the working cation (or its precursor) across theelectrode/electrolyte interfaces, R_(ct), and the resistance to themobility of the working cation in the electrolyte, R_(i).

The chemical reaction of a primary battery cell is not reversible, thatof a secondary battery cell is reversible on the application of acharging power P_(ch)=I_(ch)V_(ch) whereV _(ch) =V _(oc)+η_(ch)(I)  (6)and η_(ch)=I_(ch)R_(b,ch).

The efficiency of electric-energy storage in a secondary (rechargeable)battery cell is P_(dis)/P_(ch). Irreversible chemical reactions at oneor both electrodes of a secondary battery introduce a loss of the cellcapacity Q(I) on successive charge/discharge cycle numbers (n+1) and n.The Coulomb efficiency Q(I)_(n+1)/Q(I)_(n) determines the cycle life ofa secondary battery cell before ΔE_(dis) is reduced to 80% of itsinitial value.

Since the ionic conductivity inside a battery is orders of magnitudesmaller than the electronic conductivity in the external circuit, abattery cell is generally fabricated as an anode/thinelectrolyte/cathode cell with a large surface area ofelectrode-electrolyte contacts in which each electrode also contacts ametallic current collector for delivering electrons from an electrode tothe external circuit or to an electrode from the external circuit. Bothelectrodes of a cell change volume during charge and discharge, andretention of strong interfaces between an electrode and the currentcollector on one side and the electrode and the electrolyte on the otherside is associated with maintaining the chemical reaction. The volumeconstraint may limit an electrode volumetric capacity Q(I), a figure ofmerit for a battery powering an electric road vehicle, where theelectrode consists of small particles into which the working ion isinserted or alloyed reversibly or undergoes a conversion reaction.

The electrolyte of a battery cell may be a liquid, a polymer, a glass, aceramic, or a composite combination thereof. Construction of amechanically robust, flexible electrolyte that retains good interfaceswith electrodes or other electrolytes over thousands of charge/dischargecycles is desired. The construction may be more of a challenge with aglass or ceramic solid electrolyte contacting a solid electrode thanwith polymer or liquid electrolytes. The composites of glass or ceramicelectrolytes can be made with flexible polymers, resulting in a robustand flexible composite. Where the electrode is a metal that is platedand stripped or where the electrode is a metal current collector, asolid-solid contact may be stable over many charge/discharge cyclessince plating can involve a strong interfacial bond and changes only thedimension perpendicular to the interface. Where the electrode is a solidparticle that either alloys with, is converted by, or is inserted by theworking ion, the volume changes may be three-dimensional and the solidparticles may be preferentially liquid or polymer electrolyte. Where arelay or an electrode is a soluble redox molecule, the redox moleculemay contact the cathode current collector in the solvent used.

Traditional batteries may use an aqueous electrolyte that conducts H+ions, and the energy gap between the hydrogen-evolution reactions andthe oxygen evolution reaction of water is 1.23 eV, which may limit astable shelf life of an aqueous-electrolyte to a discharge voltageV(q)≤1.5 V.

An organic-liquid electrolyte conducting Li+, Na+, or K+ ions can have astable discharge voltage V(q)≤3.0 V with a long cycle life.Organic-liquid-electrolyte batteries with a higher V(q) requireformation of a passivating solid-electrolyte interphase (SEI) layer onthe surface of one or both electrodes of a secondary battery cell topassivate the electrode-electrolyte reaction where μA>LUMO and/orμC<HOMO. The LUMO and HOMO of the electrolytes are, respectively, thelowest unoccupied and highest occupied molecular orbitals of theelectrolyte. The energy gap Eg=LUMO−HOMO is referred to as the energywindow of the electrolyte.

FIG. 2 shows a schematic of the energy profile of a stable battery withan electrolyte energy window having an energy gap Eg=LUMO−HOMO. TheFermi energy of the anode is μA<LUMO and the Fermi energy of the cathodeis μC>HOMO. A Fermi energy μA>LUMO would reduce the electrolyte and aFermi energy μC<HOMO would oxidize the cathode, unless a passivating SEIlayer is provided at the electrode surface.

As is illustrated in FIG. 2, an anode with a μA>LUMO may reduce theelectrolyte and a cathode with a μC<HOMO may oxidize the electrolyte.However, a solid electrolyte (polymer, glass, ceramic, or combination ofthese) can have a large Eg with a LUMO at a higher energy than the μA ofan alkali-metal anode and a HOMO at a lower energy than a high-voltagecathode μC to provide a high-voltage, safe battery cell without anypassivating SEI at an electrode-electrolyte interface.

However, the conventional all-solid-state batteries with an alkali-metalanode have limited capacities, rates of charge/discharge, and cycle lifebecause electrode-electrolyte interfaces are difficult to achieve with aceramic electrolyte. The interfaces on the cathode side may beparticularly difficult to achieve, where the cathode consists of smallparticles to mitigate poor electronic conductivity and a large volumechange during cycling. The conductivities of the working ion in ceramicsolid electrolytes may be so low that extremely thin electrolytes havebeen used. Polymer solid electrolytes may have too low working-ionconductivity at room temperature to give an all-solid-state battery cellthat is competitive with a cell having an organic-liquid electrolyte forlarge-scale battery applications.

The present disclosure provides safe battery cells comprising a solidelectrolyte contacting an alkali-metal anode or a metallic anode currentcollector that can be plated by an alkali metal. The solid electrolyteis wet by the alkali metal and has a LUMO>μA. The alkali metal mayeither be plated on a cathode current collector with Fermi energy μcc<μAor on a surface conductive film, such as carbon, on the currentcollector having an electrochemical potential μf with μcc<μf<μA.Optionally a catalytic relay having a redox μox, when μcc<μox<μf may beused. The catalytic relay (molecule, film, particle) may make electroniccontact with the current collector and may reduce the working ion at thecell before relaying the working ion to the current collector(with/without the surface film) for plating as a cathode at a dischargevoltage. The catalytic relay may be used whether or not a surface filmis present at the current collector.V _(dis)≲(μ_(A)−μ_(ox))/e  (7)e is the magnitude of the electron charge.

Alkali-metal anodes can be plated or stripped reversibly withoutdendrite formation with a liquid, polymer, ceramic, or glass/amorphouselectrolyte having a surface that is wet by the alkali metal. Theglass/amorphous Li+ or Na+ solid electrolyte (Li-glass or Na-glass) mayhave a working-cation conductivity comparable to that of anorganic-liquid-electrolyte. The glass/amorphous solid electrolyte may bewet by an alkali-metal anode, and may contains a high concentration ofelectric dipoles that can be oriented parallel to one another to providea large dielectric constant. The Li-glass and Na-glass electrolytes havebeen reduced to practice for the four embodiments of this disclosuredescribed with respect to FIGS. 3-8.

Plating of an alkali metal onto a metallic current collector that is notwet by the alkali metal may be dendrite-free if the working cations arereduced before reaching the current collector. If the catalyticredox-center relay for the cathode plating has a redox energy μox>μcc,where μcc is the electrochemical potential (Fermi energy) of themetallic current collector, the electrons from the anode during batterydischarge, or from the current collector during the supercapacitordischarge, may go to the working cations via the redox relay center. Theopen-circuit voltage that can be realized by theplating-battery/supercapacitor cell is given by:V _(oc)=(μ_(A)−μ_(ox))/e  (8)If a redox-relay is needed to plate the alkali metal on the currentcollector, the open-circuit voltage is given by:V _(oc)=(μ_(A)−μ_(cc))/e  (9)If the redox-center relay is not needed; e is the magnitude of theelectron charge. Therefore, to optimize the cell open-circuit voltageV_(oc), a metallic current collector may be selected with a low-energyμ_(cc) such as copper (Cu), nickel (Ni), zinc (Zn), silver (Ag), gold(Au), or, alternatively, a metallic compound such as a transition-metaloxide or sulfide.

The metal plating-battery/supercapacitor cell disclosed herein canprovide a safe high-voltage battery cell with a high capacity ofelectrical-energy storage as chemical energy and a sufficient capacityof an extremely high-rate electrostatic energy storage having a longcycle life and a storage efficiency approaching 100%. The disclosedmetal plating-battery/supercapacitor cell is an all-solid-stateplating-battery/supercapacitor cell with a Li-glass or Na-glasselectrolyte. The metal plating-battery/supercapacitor cell disclosedherein can provide a battery cell without dendrite formation on ametallic current collector with the aid of a catalyticredox-center-relay that makes electronic contact with the currentcollector. The metal plating-battery/supercapacitor cell disclosedherein can provide a novel plating-battery cell that stores electricpower as chemical energy in an alkali-metal anode that is discharged byplating the anode metal onto a cathode current collector of lowerelectrochemical potential (Fermi energy) than that of the anode,optionally using a catalytic redox center that reduces the workingcation of the cell and relays the working cation to the cathode currentcollector for plating to provide a primary battery cell, and the alkalimetal can be returned to the anode on charge to provide a secondarybattery cell. The metal plating-battery/supercapacitor cell disclosedherein can provide a metal plating-battery/supercapacitor cell thatcombines storing electricity as chemical energy as in a metal platingbattery and storing electric power as electrostatic energy as in asupercapacitor The metal plating-battery/supercapacitor cell disclosedherein can provide a cell comprising anode and cathode currentcollectors of different Fermi energy in which the electric power storedis primarily electrostatic energy but is also stored by plating theworking cation of the electrolyte as a metal on the anode currentcollector. With load resistance R_(L) on discharge and an internalbattery resistance R_(b,dis), the amount of plated anode may remainfixed to give a continuous discharge current I _(dis) through the loadif the energy I_(dis)(R_(L)+R_(b,dis)) is supplied by external heatapplied to the cell. A battery with cells in parallel may have a smallenough I_(dis) to give a sustained work output I_(dis)R_(L) at a modesttemperature.

The metal plating-battery/supercapacitor cell disclosed herein may be aplating-battery/supercapacitor cell that uses a solid electrolyte withan ionic conductivity comparable to that of an organic-liquidelectrolyte and a large dielectric constant associated with electricdipoles that can be oriented parallel to one another, optionally with aliquid or polymer contacting one or both electrodes. The metalplating-battery/supercapacitor cell disclosed herein may enable storageof electric energy in a secondary plating-battery/supercapacitor cell, ahigh-capacity, primary plating-battery/supercapacitor cell, or a metalplating battery in which the cations of the metal plated on the anodecurrent collector are supplied by the electrolyte.

In the metal plating-battery/supercapacitor cell disclosed herein, thedischarge and charging currents of the cells may be increased by heat,which decreases the ionic resistivity Ri of the electrolyte and thecharge-transfer resistance across electrode-electrolyte and anyelectrolyte-electrolyte interfaces, when present.

In the metal plating-battery/supercapacitor cell disclosed herein,plating of an alkali metal on a current collector is provided where thecurrent collector is copper at the cathode of a plating battery cell,FIGS. 3-6.

FIG. 3 shows a plot of discharge voltage versus the capacity of a Li/Scell in the form of a Li/Li-glass/Cu cell containing a sulfur (S) relay.In FIG. 3, the capacity is shown relative to the capacity to reduce allthe S to Li2S to show that the capacity of a cell acting as a primarycell is the capacity to plate the anode lithium onto the cathode ratherthan to reduce the S relay to Li2S.

FIG. 4 shows a plot of discharge voltage versus the capacity of the Li/Scell of FIG. 3 relative to the capacity of the lithium anode to show aplating of up to 90% of the lithium of the anode on the cathode currentcollector with the aid of the sulfur relay.

FIG. 5 shows a plot of storage efficiency and coulombic efficiency ofelectric-power storage in the Li/S cell of FIG. 3 with adischarge/charge cycle of 10 h charge, 2 h rest, 10 h discharge, 2 hrest for a large number of cycles. It is noted that the data collectionin FIG. 5 is ongoing after 1000 hours.

FIG. 6 shows a plot of storage efficiency and coulombic efficiency ofelectric-power storage in a Na/Na-glass/Cu cell with a ferrocenemolecule as the redox center for plating sodium on a copper currentcollector.

FIG. 7 shows a plot of charge/discharge voltage profiles versus time ofa Li/S cell, in which the cell is self-charged, during which some Li+from the electrolyte is plated on the anode. In the Li/S cell, theplating of Li+ on the anode reduces the capacity of the electrostaticenergy stored and therefore the voltage with each successive cycle. Thedata point on the voltage plot from self-charge to discharge indicate afast initial voltage change (where no data point could be acquired)followed by a measurable rate of voltage change.

FIG. 8 shows a charge/discharge voltage plot of an Al/Li-glass/Cu cellshowing, inset, an increase to over 100% in the coulomb efficiency ofelectric-power storage on successive self-charges at open-circuit owingto plating of metallic lithium on the aluminum anode.

In the metal plating-battery/supercapacitor cell disclosed herein, aprimary plating-battery cell having a lithium anode, a glass/amorphouselectrolyte, a copper current collector and an elemental-sulfur redoxcenter relay contacting the current collector with carbon is provided,FIGS. 3, 5, 7, and 8.

In the metal plating-battery/supercapacitor cell disclosed herein, asecondary plating-battery/supercapacitor is provided with a sodiumanode, a ferrocene redox-center relay and a copper current collector,FIG. 6, and a Li-glass cell with an aluminum anode current collector anda copper cathode current collector is disclosed without the addition infabrication of lithium to the aluminum current collector, FIG. 8.

The present disclosure provides a method of plating an alkali metalwithout dendrites on a metal current collector that is normally not wetby the alkali-metal with the aid of a redox material contacting thecurrent collector that may reduce the alkali-metal cation before thealkali-metal cation is plated on the redox material or relayed to thecurrent collector.

The present disclosure also includes a metal plating-battery cell,either primary or secondary, that uses an alkali-metal anode that may beplated dendrite-free on the alkali-metal from the electrolyte and may beplated on a cathode current collector having a Fermi energy at a lowerenergy than that of the anode with the aid of a redox intermediarymaterial. In any of the disclosed embodiments of the metalplating-battery cell, plating on the cathode current collector may beperformed without the aid of a redox material intermediary. The metalplating-battery cell may use sulfur as the redox intermediary. The metalplating-battery cell may use ferrocene as the redox intermediary. Themetal plating-battery cell may use silicon as the redox intermediary.The metal plating-battery cell may use sulfide as the redoxintermediary. The metal plating-battery cell may use an oxide as theredox intermediary. The metal plating-battery cell may use a solid-glasselectrolyte and combines chemical and electrostatic storage of electricpower. The metal plating-battery cell may use a metallic compound as thecathode current collector. The metal plating-battery cell may use carbonon a current collector to aid plating of an electrode on the currentcollector. The metal plating-battery cell may use a gold film on thecathode-collector surface. The metal plating-battery cell may use anoxide film on the cathode current collector. The metal plating-batterycell may be used in a plating-battery/supercapacitor secondary batterycell. The metal plating-battery cell may be used in a plating-battery orplating-battery/supercapacitor cell.

The present disclosure also includes an electrochemical containing ananode current collector of a higher Fermi energy than that of thecathode current collector and a solid Li+ or Na+ glass/amorphouselectrolyte with a high dielectric constant that, on charge, storeselectric power as electrostatic energy and as chemical energy by platingsome of the electrolyte working ions on the anode. At open-circuitvoltage, plating of the working ions on the anode may proceed byself-charge to increase the capacity of the cell discharge. Theelectrochemical cell may have an aluminum anode and a copper cathode. Inthe electrochemical cell, the metal of the working ion may be added tothe anode current collector. In the electrochemical cell, the cathodecurrent collector may be copper (Cu), zinc (Zn), silver (Ag), gold (Au),silicon, a sulfide, or an oxide. In the electrochemical cell, anelectronically conducting material of large surface area may be thecurrent collector to increase the electrode-electrolyte contact area forstoring electrostatic charge. The electrochemical cell may have a loadin an external circuit of small resistance RL such as an LED or anelectronic device and also a small internal battery resistance Rb,dissuch that the Idis(RL+Rb,dis) loss is less than the energy suppliedexternally by heat, thereby creating a continuous Idis.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents and shall not be restricted or limited bythe foregoing detailed description.

The invention claimed is:
 1. A method of operating an electrochemicalstorage cell comprising a battery comprising: an alkali metal anodehaving an anode Fermi energy; an electronically insulating, amorphous,dried solid electrolyte able to conduct alkali metal, having the generalformula A_(3-x),H_(x)OX, wherein 0 ≤x ≤1, A is the alkali metal, and Xis at least one halide; and a cathode comprising a cathode currentcollector having a cathode Fermi energy lower than the anode Fermienergy; and a catalytic redox-center-relay material, the methodcomprising: plating the alkali metal dendrite-free from the solidelectrolyte onto the alkali metal anode and, plating the alkali metal onthe cathode current collector with the aid of the catalyticredox-center-relay material.
 2. The method of claim 1, wherein thealkali metal is lithium (Li).
 3. The method of claim 1, wherein thealkali metal is sodium (Na).
 4. The method of claim 1, wherein the solidelectrolyte further comprises a glass-forming additive comprising atleast one of Ba(OH)₂, Sr(OH)₂, Ca(OH)₂, Mg(OH)₂, Al(OH)₃, BaO, SrO, CaO,MgO, Al, B₂O₃, Al₂O₃, SiO₂, S, and Li₂S.
 5. The method of claim 1,wherein the solid electrolyte further comprises less than 2 mole percentof a glass-forming additive.
 6. The method of claim 1, comprisingstoring power in the battery both chemically and electrostatically dueto the solid electrolyte.
 7. The method of claim 1, wherein the cathodecurrent collector comprises a copper (Cu), silver (Ag), zinc (Zn), orgold (Au) metal, or an alloy thereof.
 8. The method of claim 1, whereinthe catalytic redox-center-relay material comprises sulfur.
 9. Themethod of claim 1, wherein the catalytic redox-center-relay materialcomprises ferrocene.
 10. The method of claim 1, wherein the catalyticredox-center-relay material comprises silicon.
 11. The method of claim1, wherein the catalytic redox-center-relay material comprises asulfide.
 12. The method of claim 1, wherein the catalyticredox-center-relay material comprises an oxide.